Italian premier Silvio Berlusconi is in pain, having trouble eating and remains in hospital following an attack by a mentally ill man that broke his nose and two teeth, doctors said.
Doctors said they had ordered Mr Berlusconi, 73, to cancel or reduce public appearances for two weeks, meaning he will not attend the climate talks in Copenhagen.
They had previously said he would be released from hospital yesterday, but it is now expected to be this afternoon.
Mr Berlusconi's personal doctor said he was not worried that the prime minister's overall health was in danger from injuries he suffered when a souvenir metal statuette of Milan's cathedral was hurled into his face at close range at a rally in the city.
Police tightened security around Mr Berlusconi following the attack but said another mentally disturbed man was still able to reach the floor of the Milan hospital where the premier was being treated early yesterday morning.
But an anti-terrorism official asserted that the incident did not reflect a new security failure, because they had put checkpoints only on the floor where Mr Berlusconi was being treated, and the man was stopped at the first checkpoint.
The official said the unarmed 26-year-old from Turin "wanted to pay a visit on the premier at 2am", and said he was a supporter of Mr Berlusconi.
The premier's spokesman, Paolo Bonaiuti, said Mr Berlusconi had a "rough night" on Tuesday.
The prime minister is fending off a sex scandal and legal troubles and he has decried what he calls a "climate of hatred" against him.